High temperature development process using 3-pyrazolidones in acid media



United States Patent 3 261 685 HIGH TEMPERATURE DliEVELOPMENT PRQCESS USING S-PYRAZULIDQNES 1N ACED MEDIA Louis Be Haes, Edegem-Antwerp, and Andre Rott,

Antwerp, Belgium, assignors to Gevaert PiilGiQ-Pfflt'illfiten N.V., Mortsel, Belgium, a company of Belgium No Drawing. Filed Sept. 21, 1965, Ser. No. 439d80 Claims priority, application Netherlands, Jan. 20, 1961, 260,300 12 Claims. (Cl. 96-66) This application is a continuation-in-part of our application Serial No. 167,427, filed January 19, 1962, under the same title, now abandoned.-

This invention relates to a new process for the development of exposed silver halide emulsion layers, more especially to a rapid developing rocess, and to photographic light-sensitive material used therein.

Development of photographic silver halide emulsion layers is normally carried out in an alkaline medium in the presence of an organic developing substance. As is well known, the function or the alkali in such a developing process is twofold:

(1) It promotes the ionization of the developing substance as to enable a sutlicient amount of the resulting ions to take part in the reaction;

(2) It neutralizes the halogen hydracid set free during development on the surface of the silver grain, whereby the reaction equilibrium is so shifted as to promote and consequently strongly accelerate the development process.

The provision of alkali, however, has the disadvantage of rendering the photographic baths subject to aerial oxidation and, thus unstable. Another disadvantage is that an alkali residue builds up in the subsequent treating baths, e.g. the acid fixing bath and neutral stabilizing bath, whereby their chemical composition becomes a!- tered and their function impaired.

Moreover, the particular susceptibility of standard developing agents to oxidation in the presence of alkali gives rise to other dihiculties. The resultant oxidation products are colored, typically yellow. Thus, prints developed in an alkaline bath containing one of these agents tend, as is well known, to yellow or otherwise lose their whiteness with age on account of the oxidation of the retained developer intensified by residual alkali. While this tendency is undesirable for virtually any photographic print, it is especially objectionable in the case of copies obtained by means of the difiusion transfer process. This is true because the great bulk of business and personal documents to be copied, such as reports and correspondence, are positives having large amounts of white background area where yellowing would be immediately apparent. Again, self-contained photographic materials carrying the developing agent within the light-sensitive layer or a superposed layer are known to have definite virtues for certain purposes. However, if such a material is provided with the alkali in situ, its keeping qualities are poor while, otherwise, the principle benefit of requiring only the addition of plain water for development is lost.

It has now surprisingly been found that an exposed silver halide emulsion layer can be satisfactorily developed using a S-pyrazolidone derivative as the developing substance at a pH which is less than 7, provided the temperature of the developing bath is sufi'lciently high.

The 3-pyirazolid'one derivatives are themselves known developing agents, being commonly employed in conjunction with hydroquinone. The performance of the best known member of this group, 1-phenyl-3-pyrazolidone, has been examined quite extensively under experimental conditions and the results published in an article by James and Vanselow, The Kinetics of Development by 1-Phenyl-3-Pyrazoliclone, Photographic Science and Technique, PSA Technical Quarterly, August 1954, pp. 77-80. The tests performed included determinations of the effect on the rate of development of variations in the pH and in the temperature of the developing bath. The former showed development proceeded at an extremely slow rate in the region of neutrality and below, whereby the density obtained at prl 5 .5 with eight minutes development time being only about 20% of that obtained at about pH 9 with three minutes development time. The latter showed the temperature dependence of the rate of development followed a simple Arrhenius curve over the range of 540 C. at pl-Is varying from 6.5 to 13.5. This means that at increasing temperature the rate of development increases in a lessening rate approaching some limiting value. Consequently one would logically expect that further increases in temperature above the maximum temperature of C. of the above. James article, would produce no significant increase in the rate of development.

In distinct and surprising contrast to the results to be reasonably expected on the basis of the work just summarized, it has been found that photographic development using a 3 pyrazolidone derivative as the developing agent can be carried out in an acid medium to achieve satisfactory levels of reproduction with quite brief periods of contact with the developing agent, provided the development bath is maintained at a sufficiently high temperature and at least within the range of to C. This unexpected achievement is the fruit of the discovery that the rate of development with the derivatives in question in an acid medium undergoes a sharp increase in the region of 45 C. and above, reaching far higher densities than the previous progression of that rate at ordinary working temperatures would indicate. By operating in this region, etl'ective iniage densities can be obtained even with very short periods of development, a is desirable if not essential for the production of copies by the diffusion transfer process, a result which would be considered to be out of the question in the light of the knowledge of the art as represented by the above-mentioned publication.

3-pyrazolidone derivatives useful as developing sub stances in the process according to the present invention correspond to the following general formula R represents an aryl radical, substituted or unsubstituted,

R represents a hydrogen atom or an acyl radical, such as an acetyl radical,

each of R R R and R (equal or different) represents a hydrogen atom, an alkyl radical, substituted or unsubstituted, and an aryl radical, substituted or unsubstituted.

The following are examples of 3-pyrazolidone derivatives which appeared from existing experimental work to give particularly interesting results:

1-phenyl-3-pyrazolidone 1- m-tolyl -3 -pyrazolidone 1-phenyl-2-acetyl-3-pyrazolidone 1-phenyl-4-methyl-4-pyrazolidone 1-phenyl-5-methyl-3-pyrazolidone 1-phenyl-4,4dirnethyl-3 -pyrazolidone l-phenyl-S ,5 -dimethyl-3-pyrazolidone 1,5 -diphenyl-3-pyrazolidone 1- m-tolyl) -5-phenyl-3 pyrazolidone 1- (p-tolyl) -5-phenyl-3 -pyrazo1idone.

aaereaa The 3-pyrazolidone derivative employed in this invention can be dissolved in an aqueous solution, which may occasionally be buffered. The developing substance may also be incorporated directly in the silver halide emulsion layer, or in a pre-coat or an after-coat for that layer in which event the resultant developer-containing material can then be developed simply by means of water at 45 to 100 C.

The quantity of developing substance that is used can amount to 10 to 300 g./mol of silver halide present in the light-sensitive material. Best results, however, have been obtained with 100 g./mol of silver halide.

As light-sensitive emulsions, silver chloride emulsions, silver bromide emulsions, silver iodide emulsions or emulsions of mixtures of these silver halides can be applied.

The amount of silver halide provided in the light-sensitive material may vary from an amount equivalent to 0.3 g. of silver to an amount equivalent to 3 g. of silver/sq.m. but optimally amounts to the equivalent of 1 g. of silver/ sq.m.

To the silver halide emulsion layers the usual ingredients may be added, such as ingredients for obtaining a neutral image tone, hardening agents, stabilizing agents and development activators.

As ingredients in order to obtain a neutral image tone, l-phenyl-S-mercapto-1,2,3,4-tetrazole and the products described in British patent specifications 561,875 and 695,905 may be used. As development activator, Naloamine G13 (trade' name for 1(,B-hydroxyethyD-Z-(heptadec-S-enyl)-A -imidazoline, marketed by National Aluminate Corporation, Chicago, Illinois, U.S.A.), can successfully be used.

After development, the exposed material has to be fixed or stabilized. Suitable fixing agents are, e.g. sodium thiosulfate, and its substitution products, such as ethyl sodium thiosulfate.

Suitable stabilizing agents are e.g. 1,3-trimethylenethiourea, 2-thio-perhydro-s-triazine-2-one, 2-thio-5-methylperhydro-s-triazine-Z-one, 2-thio-4-hydroxy-4-methyl-perhydropyrimidine-2-one and 4-morpholinyl-thiocarbonarnide. The used concentrations of these compounds may vary between 0.5 and 5% dependent on the temperature of the liquid and the travelling rate of the material through the bath.

A specially interesting embodiment of the new process consists in carrying out the development in a solution of the fixing agent or stabilizing agent instead of in warm water. The concentration and the temperature can then be chosen in such a way that the development has a sufficient lead on the fixation or stabilization, so that the complete formation of the image can be realized by one single treatment in a single bath.

The new process can successfully be practiced with materials which are suited for use in the silver complex diffusion transfer process. The details of this process and the materials employed therein are described in the British patent specifications 614,155, 654,630 and 654,631 and in the German patent specification 887,733.

The following examples illustrate the present invention.

Example I Onto a paper support is coated a silver chlorobromoiodide emulsion layer from the following composition: Silver chlorobromoiodide emulsion containing an amount of silver halide equivalent to 50 g. of silver per liter g 1000 Water cm. 1240 40% aqueous formaldehyde cm. 5 Nalcamine G13 (trade name) g 20% aqueous saponine cm. 5

This emulsion is coated in such a way that 1 liter of this composition covers 13 sq. m. of paper. After drying, the obtained light-sensitive material is exposed and subsequently developed for 2 sec. in 1% aqueous solu- 4 tion of 1-phenyl-3-pyrazolidone heated to C. and having a pH of 4.4.

Then the developed material is stabilized at room temperature in a solution of the following composition:

Thiourea g Water cm. 100

Example 11 Onto a paper support is coated a silver chloride emulsion layer from the following composition:

Silver chloride emulsion containing per liter an amount of silver chloride equivalent to 29 g. of silver g 1000 Water cm. 500 5% solution of l phenyl 3 pyrazolidone in ethanol cm. 500 40% aqueous formaldehyde cm. 5 20% aqueous saponine cm. 5

The emulsion is applied in such a way that 1 liter of this composition covers 20 sq. m. of paper. After drying, the obtained light-sensitive material is exposed and then developed for 2 sec. in water of 80 and pH of 5.7. Thereupon, the developed material is stabilized as in Example I.

Example II] On a paper support is coated a silver chloride emulsion layer from the following composition:

Silver chloride emulsion containing per liter an an amount of silver chloride equivalent to 15 g.

of silver g 1000 40% aqueous formaldehyde cm. 2.5 20% aqueous saponine cm. 2.5

This emulsion is coated in such a way that 1 liter of this composition covers 20 sq. m. of paper. Then an after-coat is applied on top thereof from a 5% solution of l-phenyl-3-pyrazolidone in ethanol. The material is then further treated as in Example II.

Example IV Onto a paper support a pre-coat is applied from the following solution at 35 C.:

Water cm. 395 Gelatin g 50 10% solution of 1 (p tolyl) 5,5 dimethyl 3- pyrazolidone in ethanol cm. 550 20% aqueous saponine cm. 5

This pre-coat is applied in such a way that 1 liter of this composition covers 10 sq. m. of paper. Onto this pre-coat, a silver chloride emulsion layer is applied from the following composition:

Silver chloride emulsion containing per liter an amount of silver chloride equivalent to 15 g. of

covers 20 sq. m. of paper. After drying, the obtained light-sensitive material is exposed and then simultaneously developed and stabilized for 5 sec. in a C.

warm solution of the following composition:

Thiourea g 2 Water cm.

which provided an effective pH in the emulsion layer of 6.0.

Example V A light-sensitive photographic material is manufactured by applying onto a paper support a silver chloride emusion layer from the following composition:

Silver chloride emulsion containing per liter an amount of silver chloride equivalent to 15 g. of

silver g 1000 40% aqueous formaldehyde cm. 2.5 20% aqueous saponine cm. 2.5

An image-receiving material is manufactured by applying onto a paper support a nuclei-containing layer from a suspension of the following composition:

Water cm. 200 Gelatin g Zinc sulfide g 0.04 20% aqueous saponine cm. 2

After image-wise exposure, the light-sensitive material together with the image-receiving material are carried through a diffusion transfer developing apparatus containing an 80 C. warm treating liquid of the following composition, having a pH of 5.3:

Water cm. 1000 Sodium thiosulfate (anhydrous) g 5 1-pheny1-3-pyrazolidone g 20 After being squeezed between the rubber rollers of the developing apparatus and after a contact-time of about 10 sec., both materials are separated. A positive copy of the original is obtained.

Example VI A photographic material is prepared by applying onto a paper support a nuclei-containing layer from a suspension of the following compositon:

Water cm. 50 10% aqueous gelatin cm. 30 Sodium sulfide g 0.023 Cobaltous nitrate g 0.091 5% solution of 1 phenyl 3 pyrazolidone in ethanol cm. 20 40% aqueous formaldehyde cm. 1

After drying, a light-sensitive emulsion layer is applied thereon from the following composition:

Gelatino-silver chloride emulsion containing per liter an amount of silver chloride equivalent to 29 g. of

silver g 100 5% solution of l-phenyl-B-pyrazolidone in ethanol crn. 30 Water cm. 20 20% aqueous saponine cm. 1

After drying, this light-sensitive material is image-wise exposed and developed for 30 sec. in the following developing composition at 50 C.:

Water cm. 1000 Sodium sulfite (anhydrous) g 5 Soduim bisulfite (anhydrous) g 5 Sodium thiosulfate (anhydrous) g 7 which provided an effective pH at the emulsion layer of 6.6

The image is apparent after a few seconds and the emulsion spontaneously dissolves. In this way a positive copy of the original is obtained.

Example VII-XI Five tests strips of a light-sensitive negative-forming material prepared as described in Example I above are similarly exposed and then dipped one :by one for 1 second into a 1% aqueous solution of l-phenyl-3-pyrazolidone which is maintained at a pH of 5.9 by means of a buffering agent, the temperature of the bath being adjusted to 20 C. for the first strip and then raised 20 C. for each succeeding strip, reaching 100 C. for the last. After dipping, the strips are immediately stablized as in Example I.

The maximum density and fog levels are determined for each strip and are summarized in the following tabulation:

TABLE 1 Test Strip No VII VIII IX X XI Solution Temperature, C 20 40 60 100 Maximum density 0.01 0. 14 0. 55 0. 74 0. Fog 0. 00 0. 00 0. 01 0. 02 0. 07 Difference (Du n-Fog) 0. 01 0. 14 0. 54 0. 72 0. 88

Examples XII-XVI Another set of tests strips is processed as described in Examples VII-XI except that the bath is maintained at a pH of 4.5 and the dipping time is extended to 15 seconds. The maximum density and fog levels are determined as before with the following results:

TABLE 2 Test Strip No XII XIII XIV XV XVI Solution Temperature, C 20 40 60 80 Maximum Density I- 0.06 0.13 0.48 0.65 0.79 Fog 0.00 0.00 0.01 0.03 0.07 Difference (Dmnx,-FOg) 0. 06 0.13 0.47 0.62 0.72

Examples X VII-XX Examples VllXI are repeated at the first four bath temperatures except that the dipping time is extended to We claim:

1. A process of photographic reproduction comprising subjecting a photographic material comprising a support and an exposed photographic silver halide emulsion layer on one side of said support to development with a 3 pyrazolidone developing agent, said development being carried out by treating said exposed photographic silver halide emulsion layer with an aqueous solution in the presence of said 3-pyrazoliclone developing agent at a pH of less than 7 and at a temperature from 45 C. to 100 C.

2. The process of claim 1, wherein said 3-pyrazolidone developing agent corresponds to the general formula R5C N-R2 R O'-C I=O a wherein:

R is an aryl radical, R is a member selected from the group consisting of a hydrogen atom and an acyl radical, and each of R R R and R is a member selected from the group consisting of a hydrogen atom, an alkyl radical, and an aryl radical.

3. The process of claim 2, wherein said development is carried out between 50 and 100 C.

4. The process of claim 2, wherein said aqueous solution contains a fixing agent for silver halide.

tion contains a stabilizing agent for silver halide.

6. The process according to claim 2, wherein said 3- pyrazolidone developing agent is present in said silver halide emulsion layer.

7. The process of claim 2 wherein said 3-pyrazolidone developing agent is present in a Water-permeable layer which is coated on the same side of said support as said sliver halide emulsion layer.

8. The process of claim 2, wherein said 3-pyrazolidone developing agent is present in both said light-sensitive silver halide emulsion layer and in a water-permeable layer which is coated on the same side of said support as said silver halide emulsion layer.

9. The process of claim 2, wherein said silver halide emulsion layer after being contacted with said aqueous solution in the presence of said developing agent is maintained in contact for image formation by means of silver '8 complex diffusion transfer with an image-receiving layer containing nuclei, said emulsion layer being thereafter removed from said image-receiving layer.

10. The process of claim 9, wherein said layers are maintained in contact for up to about 30 seconds.

11. The process of claim 9, wherein said image-receiving layer is carried on the same side of the same support which carries said emulsion layer.

12. The process of claim 2, wherein said emulsion layer contains sutficient silver halide to provide about 0.3-3 grams of silver per square meter of surface area and said developing agent is present in an amount of about 10-300 grams per mol of said silver.

No references cited.

NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner. 

1. A PROCESS OF PHOTOGRAPHIC REPRODUCTION COMPRISING SUBJECTING A PHOTOGRAPHIC MATERIAL COMPRISING A SUPPORT AND AN EXPOSED PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER ON ONE SIDE OF SAID SUPPORT TO DEVELOPMENT WITH A 3PYRAZOLIDONE DEVELOPING AGENT, SAID DEVELOPMENT BEING CARRIED OUT BY TREATING SAID EXPOSED PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER WITH AN AQUEOUS SOLUTION IN THE PRESENCE OF SAID 3-PYRAZOLIDONE DEVELOPING AGENT AT A PH OF LESS THAN 7 AND AT A TEMPERATURE FROM 45*C TO 100*C. 